1. Field of the Invention
The present invention relates to a method of cutting chemically toughened glass, and more particularly, to a method of cutting a piece of chemically toughened glass in which compressive stress is created in the surface of the chemically toughened glass.
2. Description of Related Art
Glass products are treated as indispensable components in a variety of technological and industrial fields involving image and optical equipment, such as monitors, cameras, video tape recorders (VTRs) and mobile phones, transportation equipment, such as vehicles, various types of tableware, construction facilities, and the like. Accordingly, glass products having a variety of physical properties that meet the requirements of respective industrial fields are manufactured and used.
In particular, recently, chemically toughened glass is widely used as cover substrates for displays including organic light-emitting displays (OLEDs), liquid crystal displays (LCDs), plasma display panels (PDPs) and field emission displays (FEDs).
Methods of toughening glass include a physical toughening method and a chemical toughening method. The physical toughening method, also referred to as air-cooled toughening, is mainly applied to the safety glass of a vehicle. The chemical toughening method is a technology that can be usefully applied to a thin glass sheet that has a complicated shape or a thickness of about 2 mm or less. The chemical toughening method exchanges alkali ions having a small ion radius (generally Na ions) that are present inside a piece of glass with alkali ions having a large ion radius (generally K ions) under predetermined conditions. A great amount of compressive stress is created in the surface of the chemically toughened glass due to the ion exchange, thereby increasing the strength and hardness of the glass.
However, the chemically toughened glass has the drawback in that, after the glass is toughened, it is substantially impossible to perform secondary machining, such as cutting or grinding, due to the compressive stress present in the surface of the chemically toughened glass. When it is attempted to cut the chemically toughened glass using a related-art diamond wheel, the glass will break into irregular fragments instead of into an intended shape due to the large compressive stress present in the surface of the glass.
Accordingly, in the related art, chemically toughened unit glass having an intended size or shape is manufactured by cutting or grinding a large piece of glass and then performing chemical toughening on the cut or ground piece of glass. However, the process of manufacturing such chemically toughened unit glass has the problem of low process efficiency and productivity.
Therefore, in order to manufacture chemically toughened glass having a variety of sizes and shapes at high process efficiency and productivity, the development of a technology for cutting the chemically toughened glass is required.
In this regard, United States Patent Application Publication No. 2012/0064306 disclosed a technology of cutting chemically toughened glass after the glass is chemically toughened. Here, the chemical toughening is performed after a shielding layer which prevents ion exchange is formed from polymers or the like at a portion to be cut. However, there are several limitation factors. That is, the shielding layer must withstand a high-temperature environment of a chemical toughening temperature, i.e. a temperature similar to the glass transition temperature, and the shielding layer must be easily removed after the chemical toughening process.
In addition, United States Patent Application Publication No. 2010/0206008 disclosed a technology of cutting chemically toughened glass using a laser. However, the use of the laser is not efficient for productivity, which is problematic.
Furthermore, United States Patent Application Publication No. 2012/0135195 disclosed a technology of cutting chemically toughened glass by forming a tensile area in the surface of the chemically toughened glass through etching or the like and then propagating cracks. In this case, however, cracks formed in the glass surface make it difficult to handle the glass during the toughening process.
The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.